It means the departure of one of the party's most respected voices in the congressional arena. It makes the Democrats' desire to retake the Senate all the more remote. And it makes more attainable the Republicans' goal of bumping up their 54-to-46 majority to control of 60 seats, the number needed to stop a bill-stalling filibuster.

The announcement by Senator Bradley, who was praised by President Clinton as "a voice for civility," also highlights the changing culture of the Senate, from one of deliberation and cooperation toward the brashness and partisan edge that now typifies the House.

"He is a genuinely committed, cerebral, issue-oriented person, who served to contribute to the public debate," says Angelo Genova, counsel to the New Jersey Democratic Party. "There is a growing view that [Congress] is not the forum for it. People like Bill Bradley get pulled down."

Bradley's announcement also keeps up the brisk pace of senatorial retirements - to date more than have been announced in the 435-member House. Save one Republican retiree, Sen. Hank Brown of Colorado, the five others bowing out are Democrats from states that could easily give their seats to Republicans in the next election: Paul Simon of Illinois, Bennett Johnston of Louisiana, David Pryor of Arkansas, James Exon of Nebraska, and Howell Heflin of Alabama.

And the Senate retiree list may grow. Sen. Claiborne Pell (D) of Rhode Island, who is reported to be unwell, is not expected to seek reelection. Others reportedly considering retirement, include Sens. Sam Nunn (D) of Georgia and Nancy Kassebaum (R) of Kansas.

If the number of retirees goes to 11, which it could, that would be a post-World War II record.

Compounding the Democrats' woes, Bradley's retirement statement left little doubt of what he thinks of his party, and didn't rule out an independent run for the presidency. He also had no kind words for the Republicans.

Bradley called the political system "broken," and complained that "the political debate has settled into two familiar ruts."

"The Republicans are infatuated with the magic of the private sector and reflexively criticize government as the enemy of freedom, and the Democrats distrust the market, preach government as the answer to our problems and prefer the bureaucrat they know to the consumer they can't control. Neither party speaks to people where they live their lives."

Bradley's departure will take a certain star quality away from his corner of the Capitol. He was a basketball great for the New York Knicks, a Rhodes scholar, and was the youngest member of the Senate when first elected in 1978. During the '80s, he was a leading voice on tax reform and US-Soviet relations, and was often mentioned as a top prospect for the Democratic presidential nomination. But after his tough reelection battle in 1990 against now-Gov. Christine Todd Whitman, he seemed to lose some of his spark.

Some Democrats who know the senator commented privately that he has seemed bored with the job in recent years. "I have a pet theory," says one Democratic strategist. "Once a senator, with rare exception, makes the run mentally for the presidency and it doesn't go anywhere, they lose their edge in the Senate."

With Bradley's announcement, a dozen New Jersey politicians instantly surfaced as possible candidates. The Republicans' top prospect is Rep. Dick Zimmer, who has already been amassing a war chest for a Senate run. With $1 million in his coffers, Congressman Zimmer has displayed "the best fund-raising ability of any Republican challenger for the Senate" so far, says a Republican strategist.

Democratic congressmen Robert Torricelli and Rob Andrews have both been waiting in the wings to see if Bradley would retire. A New Jersey Democratic operative said privately that the liberal Mr. Torricelli may well win the primary, because liberal party activists tend to turn up for primaries, though Mr. Andrews might have a better shot at winning the general election.

Bradley's announcement - and the prospect of a record year for Senate retirements - prompts some philosophical musings on the changing institution.

"The nature of the body has changed as much as the process has changed as much as the times and the country have changed," says Republican consultant Eddie Mahe.

Republicans often hold up freshman Sen. Rick Santorum (R) of Pennsylvania as one of a new breed of young, partisan members who are changing the tenor of the institution. Senator Santorum won attention for putting out a "Where's Bill?" chart on the Senate floor calling attention to President Clinton's refusal to submit a balanced-budget plan. Santorum kept the display up even after Clinton unveiled his plan.